1. Field of the Invention
The present disclosure relates to an image pickup apparatus, an image pickup system, a driving method for an image pickup apparatus and a driving method for an image pickup system.
2. Description of the Related Art
A technique capable of reducing noises that may be caused by high-frequency components (e.g., aliasing distortion and moire) is conventionally proposed. As discussed in Japanese Patent Application Laid-Open No. 11-275367, it is known to the present inventors that moire can be reduced when moving average filter processing is performed on an image signal output from an image pickup apparatus.
Further, as discussed in Japanese Patent Application Laid-Open No. 4-192890, it is known to the present inventors that an addition processing of pixel signals is performed by changing the combination of the pixels to be added between odd and even fields in an interlace type charge-coupled device (CCD) sensor. Performing the above-mentioned addition processing is useful to reduce the aliasing distortion.
Further, as discussed in Japanese Patent Application Laid-Open No. 2011-23825, it is known to the present inventors that adding signals of a plurality of pixels is used to reduce the number of output signals. In other words, it is expected that a higher output rate can be attained by adding signals of a plurality of pixels.
In recent years, there has been proposed an image pickup apparatus which reduces noises such as an aliasing distortion or a moire caused by a high-frequency component without use of an optical low-pass filter. In an image pickup apparatus described in Japanese Patent Application Laid-Open No. 2006-270658, electric charges generated in one photoelectric conversion unit are transferred to two output circuits. The two output circuits are disposed such that they are mutually shifted by one photoelectric conversion unit in row and column directions. Electric charges are transferred to each of the two output circuits from four photoelectric conversion units therearound. The transferred electric charge in each output circuit is then mixed to output an electric signal. It is therefore deemed possible to reduce the aliasing distortion by synthesizing image data obtained from the two output circuits without using the optical low-pass filter.
In addition, Japanese Patent Application Laid-Open No. 2003-009003 discloses to hold a signal amplified by an in-pixel amplification unit in a capacitance of each pixel, and to add the signals held by the capacitances of pixels.